Folding frame system with folding frame elements having diagonal member of variable length

ABSTRACT

A folding frame element includes a first hub element having a first end and a second end, a second hub element having a first end and a second end, a first strut pivotably attached at a first end and a second end to the first ends of the first hub element and the second hub element, respectively, a second strut pivotably attached at a first end and a second end to the second ends of the first hub element and the second hub element, respectively, and a diagonal member extending between the first end of the first hub element and the second end of the second hub element. The first and second struts are pivotable relative to the first and second hub elements between a closed position in which the first and second struts and the first and second hub elements are substantially parallel and the diagonal member has a first length and an open position in which the first and second struts define non-zero angles with the first and second hub elements and the diagonal member has a second length shorter than the first length.

BACKGROUND AND SUMMARY

The present invention relates to folding frame systems and, more particularly, to folding frame systems with frame element having diagonal members of variable length.

A variety of types of folding frame systems are known. My U.S. application Ser. No. 10/779,632, Collapsible Structure with Self-Locking Mechanism and Method of Erecting a Collapsible Structure, filed Feb. 18, 2004, and my U.S. application Ser. No. ______ (Attorney Docket No. 000002-084), Foldable Frame Element and System with Tension Lock, filed on the same date as the present application, which are incorporated by reference, disclose folding frame systems which can be locked in place by what can be referred to as a “tension lock”. In this tension lock arrangement, the frame is locked in an open position by pivotably connected strut members that are foldable from a parallel folded condition in which the struts lie substantially against each other, through a parallel open condition in which the struts are disposed substantially end-to-end, to an open locked condition slightly beyond the latter parallel condition beyond which the struts are prevented from pivoting. In this open locked condition, when a tension member is connected between points on the two struts removed from the pivot points, the tension member will prevent the struts from passing back to the parallel open or parallel folded positions unless the tension member is released or the struts are somehow deformed.

My U.S. Pat. No. 5,230,196, U.S. Pat. No. 5,444,946, and U.S. Pat. No. 6,141,934, which are incorporated by reference, disclose embodiments of folding frame systems with what can be referred to as “manual locks”. In these systems, strut pairs are arranged in scissor fashion, and, when the scissors are unfolded to open the system from a closed condition, ends of the struts are connected by hub portions that are manually locked together.

It is desirable to provide a folding frame system that requires neither tension locks nor manual locks.

In accordance with an aspect of the present invention, a folding frame element comprises a first hub element having a first end and a second end, a second hub element having a first end and a second end, a first strut pivotably attached at a first end and a second end to the first ends of the first hub element and the second hub element, respectively, a second strut pivotably attached at a first end and a second end to the second ends of the first hub element and the second hub element, respectively, and a diagonal member extending between the first end of the first hub element and the second end of the second hub element. The first and second struts are pivotable relative to the first and second hub elements between a closed position in which the first and second struts and the first and second hub elements are substantially parallel and the diagonal member has a first length and an open position in which the first and second struts define non-zero angles with the first and second hub elements and the diagonal member has a second length shorter than the first length.

In accordance with another aspect of the present invention, a folding frame element comprises a first hub element having a first and a second end, at least a pair of strut assemblies pivotably attached to the first hub element, each strut assembly comprising a second hub element having a first end and a second end, a first strut pivotably attached at a first end and a second end to the first ends of the first hub element and the second hub element, respectively, a second strut pivotably attached at a first end and a second end to the second ends of the first hub element and the second hub element, respectively, and a diagonal member extending between the first end of the first hub element and the second end of the second hub element. The first and second struts are pivotable relative to the first and second hub elements between a closed position in which the first and second struts and the first and second hub elements are substantially parallel and the diagonal member has a first length and an open position in which the first and second struts define non-zero angles with the first and second hub elements and the diagonal member has a second length shorter than the first length. In accordance with yet another aspect of the present invention, a folding frame system comprises at least two folding frame elements connected end to end and sharing a common second hub element.

In accordance with still another aspect of the present invention, a hub element for a folding frame element is provided. The hub element comprises an elongated member and a first hub and a second hub at a first end and a second end, respectively, of the elongated member, the first hub comprising a first pivot point for pivotably connecting a first strut and the second hub comprising a second pivot point for pivotably connecting a second strut, the first pivot point being disposed at a greater distance from an axis of the elongated member than the second pivot point.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the present invention are well understood by reading the following detailed description in conjunction with the drawings in which like numerals indicate similar elements and in which:

FIGS. 1A and 1B show a folding frame element according to an embodiment of the present invention in an open and in a closed position;

FIGS. 2A and 2B show a folding frame element according to another embodiment of the present invention in an open and in a closed position;

FIGS. 3A-3D show top perspective, top, front, and side views of a folding frame system according to an embodiment of the present invention;

FIG. 4 shows a connection member for a brace for a folding frame system according to an embodiment of the present invention;

FIGS. 5A-5D are front, side, top, and bottom views of a hub element according to an embodiment of the present invention;

FIGS. 6A-6B are side and top partially cross-sectional views of a locking arrangement according to an embodiment of the present invention, FIG. 6C is a view of a component of a locking arrangement, and FIG. 6D shows the locking arrangement in use with a frame element;

FIGS. 7A-7D schematically show views of different forms of frame elements according to embodiments of the present invention;

FIGS. 8A-8D schematically show different forms of frame systems made with frame elements according to the present invention;

FIG. 9 is a front view of a frame system according to an embodiment of the present invention;

FIGS. 10A-10D are front, side, top perspective, and closed views, respectively, of a frame system according to an embodiment of the present invention;

FIGS. 11A-11E are front, side, top, top perspective open, and top perspective closed views of a frame system according to another embodiment of the present invention;

FIGS. 12A-12B are front and top views of a frame system according to another embodiment of the present invention;

FIGS. 13A-13B are front and top views of a frame system according to yet another embodiment of the present invention;

FIGS. 14A-14D show steps in the erection of a frame system of the type shown in FIGS. 10A-10D;

FIGS. 15A-15D show steps in the erection of a frame system of the type shown in FIGS. 11A-11E; and

FIGS. 16A-16C are perspective view of frame systems according to additional embodiments of the present invention.

DETAILED DESCRIPTION

FIGS. 1A and 1B show an embodiment of a folding frame element 21 for a folding frame system 23 (FIGS. 3A-3D) in an open and a closed position, respectively. The folding frame element 21 comprises a first hub element 25 having a first end 25 a and a second end 25 b, and a second hub element 27 having a first end 27 a and a second end 27 b. A first strut 29 is pivotably attached at a first end 29 a and a second end 29 b to the first ends 25 a and 27 a of the first hub element 25 and the second hub element 27, respectively. A second strut 31 is pivotably attached at a first end 31 a and a second end 31 b to the second ends 25 b and 27 b of the first hub element 25 and the second hub element 27, respectively. The hub elements 25 and 27 and the struts 29 and 31 will typically comprise elongated elements, and the elongated elements will typically be tubular elements. The tubular elements can have any desired cross-sectional profile, such as circular, square, or rectangular to name but several possibilities.

A diagonal member 33 extends between the first end 25 a of the first hub element 25 and the second end 27 b of the second hub element 27. The first and second struts 29 and 31 are pivotable relative to the first and second hub elements 25 and 27 between a closed position (FIG. 1B) in which the first and second struts and the first and second hub elements are substantially parallel and the diagonal member 33 has a first length L1 and an open position (FIG. 1A) in which the first and second struts define non-zero angles with the first and second hub elements and the diagonal member has a second length L2 shorter than the first length L1. Ordinarily, the first and second struts 29 and 31 will be parallel or substantially parallel when pivoted to the open position.

The diagonal member 33 can comprise a strut arrangement pivotably attached at a first end 33 a of the diagonal member to the first end 25 a of the first hub element 25 and at a second end 33 b of the diagonal member to the second end 27 b of the second hub element 27. The strut arrangement can comprise telescoping strut members, such as first and second telescoping strut members 33 c and 33 d that include the first and second ends 33 a and 33 d, respectively, of the diagonal member 33. The strut arrangement can comprise a lock 35 for locking the telescoping strut members 33 c and 33 d at the second length. While an embodiment including a diagonal member in the form of a strut arrangement with telescoping struts is described, it will be appreciated that other forms of diagonal members can be used, such as diagonal members in the form of cables, belts, or straps that function primarily as tension members to prevent the first and second struts from pivoting to the closed position and that can be released to permit the struts to pivot to the closed position.

As seen in FIG. 1B, when the first and second struts 29 and 31 are pivoted to the closed position, a combined length of the first strut 29 and the second hub element 27 is substantially equal to a combined length of the second strut 31 and the first hub element 25 as the two sets of strut and hub element will ordinarily lie substantially parallel to each other. In the embodiment shown in FIGS. 1A and 1B, when the folding frame element is closed (FIG. 1B) the diagonal member 33 telescopes to a greater length L1 so that it is substantially the same length as either of the sets of end-to-end strut and hub element while, when the folding frame element is open (FIG. 1A), the diagonal member retracts to and locks at the shorter length L2.

In the embodiment of the frame element 21 shown in FIGS. 1A and 1B, the frame element has first and second hub elements 25 and 27 that are intended to be substantially parallel. When the first and second hub elements 25 and 27 are substantially parallel, the frame element 21 defines a substantially rectangular shape as seen in FIG. 1A. If it is desired to form a frame element as seen in FIGS. 2A and 2B that has first and second hub elements 25′ and 27′ that are non-parallel when its first and second struts 29′ and 31′ are pivoted to the open position (FIG. 2A), such as will be useful in forming folding frame systems having, for example, “curved” or “arched” shapes, if the first and second struts are to be parallel when in the open position, then one of the first and the second struts will ordinarily be shorter than the other of the first and the second struts. Ordinarily, the first and second hub elements 25 and 27 of a frame element 21 having parallel hub elements (in the open position) are identical to the first and second hub elements 25′ and 27′ of a frame element 21′ having hub elements that are not parallel in the open position and, in a frame system 23, frame elements 21 and 21′ may share a hub element.

FIG. 2A shows an embodiment wherein the second strut 31′ is shorter than the first strut 29′ when the first and second struts are pivoted to the open position. Ordinarily, the first and second hub elements 25′ and 27′ will be the same length and, when the first and second struts are pivoted to the closed position, the combined length of the first strut and the second hub element will ordinarily be the same as the combined length of the second strut and the first hub element. Therefore, when the struts 29′ and 31′ are pivoted to the closed position, either the first strut 29′ becomes shorter or, as in the illustrated embodiment, the second strut 31′ becomes longer.

In the embodiment of FIGS. 2A and 2B, the second strut 31′ comprises telescoping strut members 31 c′ and 31 d′. Of course, if desired, the first strut 29′ might have telescoping strut members instead of, or in addition to, the second strut having telescoping strut members. In the embodiment of FIGS. 2A and 2B, when the first and second struts 29′ and 31′ are pivoted to the open position (FIG. 1A), the telescoping strut members 31 c′ and 31 d′ of the second strut are retracted to a shorter length than when the first and second struts are pivoted to the closed position (FIG. 1B). While a lock may be provided to lock the telescoping strut members 31 c′ and 31 d′ in the retracted, open position, ordinarily only the diagonal member 33′ is provided with a lock 35′.

As seen, for example, in FIGS. 1A and 1B, a tension member 37 may extend between the first end 27 a of the second hub element 27 and the second end 25 b of the first hub element 25. In the illustrated embodiment, the tension member 37 is a cable, however, other forms of tension members may be incorporated to prevent the first end 27 a of the second hub element 27 and the second end 25 b of the first hub element 25 from separating beyond a predetermined point. The diagonal member 33 can also function as a tension member by preventing the first end 25 a of the first hub element 25 and the second end 27 b of the second hub element 27 from separating beyond a predetermined point. When the diagonal member 33 is in the form of a rigid member such as a strut arrangement, the diagonal member can also function as a compression member that prevents the first end 25 a of the first hub element 25 and the second end 27 b of the second hub element 27 from moving toward each other beyond a predetermined point, thereby assisting in supporting a structure made up of frame elements 21. A cable keeper 39 may be connected to a cable or other tension member 37 to keep the tension members from being tangled during folding and unfolding. Suitable cable keepers 39 are disclosed in U.S. Pat. No. 5,230,196, which is incorporated by reference. As seen in, e.g., FIGS. 1A and 1B, one end of the cable keeper 39 may be connected proximate, e.g., the first end 29 a of the first strut 29 and the other end of the cable keeper may be connected to a point on the tension member 37 so that, when tension on the tension member is relieved, the cable keeper will prevent the cable from hanging at a random position in a manner that might encourage tangling or other problems.

A folding frame system 23 is seen in FIGS. 3A-3D. In the frame system 23, it will be seen that each folding frame element 21 (FIG. 3C) and 21′ (FIG. 3D) comprises two mirror image portions about the first hub element 25 and 25′. In other words, each second hub element 27 or 27′ has a counterpart third hub element having a first end and a second end, the first strut 29 or 29′ has a counterpart third strut pivotably attached at a first end and a second end to the first end of the first hub element and the third hub element, respectively, the second strut 31 or 31′ has a counterpart fourth strut pivotably attached at a first end and a second end to the second end of the first hub element and the third hub element, respectively, and the diagonal member 33 or 33′ has a counterpart second diagonal member extending between the first end of the first hub element and the second end of the third hub element.

While the third hub element, the third strut, the fourth strut, and the second diagonal member may be substantially mirror images of the second hub element, the first strut, the second strut, and the first diagonal member, it is not necessary that they be mirror images. For example, a frame element may comprise a “rectangular” frame element component as seen in FIGS. 1A and 1B extending from a first hub element and a “trapezoidal” frame element component as seen in FIGS. 2A and 2B extending from the same first hub element. Also, while embodiments are shown wherein frame elements comprise struts extending in opposite directions (i.e., at 180° to each other) from a first hub element, it will be appreciated that embodiments can include two or more sets of struts that extend at other angular orientations about a first hub.

In the folding frame system 23 seen in FIGS. 3A-3D, plural (at least two) folding frame elements 21 or 21′ are connected end to end and share a common second hub element 27 (for purposes of discussion, it will be understood that the second hub element 27 functions as the second hub element 27′ discussed with reference to FIGS. 2A-2B). In the illustrated embodiment, two folding frame elements 21 each having a first hub element 25 and two second hub elements 27 that are all substantially parallel to one another (see FIG. 3C) are each connected at both of their two second hub elements to folding frame elements 21′ each having a first hub element 25′ and two second hub elements that are non-parallel (see FIG. 3D) and have second struts 31′ that are adapted to telescope. The resulting frame system 23 is a three-dimensional shape that is substantially square when viewed from above (FIG. 3B) or below, rectangular when viewed from two sides (FIG. 3C), and trapezoidal when viewed from two other sides (FIG. 3D). However, any desired number of folding frame elements might be connected end to end in succession to define any polygonal shape (e.g., triangular, square, rectangular, pentagonal, etc.) with successive ones of the plurality of folding frame elements sharing common second hub elements.

The folding frame system 23 can also comprise a brace assembly 41 extending between two first struts of two non-successive folding frame elements. In the embodiment illustrated in FIGS. 3A and 3B, the brace assembly 41 extends between second ends 25 b′ of two first hub elements 25′ of folding frame elements 21′ having non-parallel second hub elements 27′, however, the brace assembly may be disposed elsewhere and the illustrated embodiment is illustrative and not limiting. The brace assembly 41 comprises two strut members 43 pivotably connected at first ends 43 a thereof to second ends 25 b′ of respective ones of the two first struts 25′ of the two non-successive folding frame elements 21′ and at second ends 43 b thereof to each other. Instead of providing a brace assembly, a folding frame system 23 can comprise folding frame elements 21 (or 21′, depending upon the shape of the folding frame system) joined by a hub element 25 (or 25′). A frame system comprising such folding frame elements is shown in FIGS. 11B-11D.

If the brace 41 extends between first hub elements 25′ of frame elements 21′ having second hub elements that are non-parallel, as in FIGS. 3A-3D, when the first and second struts of the four folding frame elements 21, 21′, 21, and 21′ are pivoted to the closed position, the two strut members 43 will ordinarily each have a first length and, when the first and second struts of the four folding frame elements are pivoted to the open position, the two strut members will ordinarily each have a second length that is shorter than the first length. This may be accomplished by forming each strut 43 from telescoping strut portions 43 c and 43 d that are adapted to be locked in the manner of the diagonal members 33 and 33′ when the struts of the frame elements are pivoted to the open position. If the strut members 43 of the brace 41 extend between first hub elements 25 frame elements 21 having second hub elements 27 that are parallel (embodiment not illustrated), the two strut members will ordinarily have the same length when the struts are pivoted to the open or the closed position.

When the first and second struts of the four folding frame elements 21, 21′, 21, and 21′ are pivoted to the open position, the first ends 25 a, 25 a′, 27 a, 27 a′ of the first and second hub elements 25, 25′, 27, 27′ generally define a first plane and the second ends 25 b, 25 b′, 27 b, 27 b′ of the first and second hub elements generally define a second plane. The second ends 43 b of the two strut members 43 are disposed substantially in the first plane. The second ends 43 b of the two strut members 43 can be pivotably connected to each other by any suitable means. A connection member 45 that prevents the strut members from pivoting beyond the first plane will ordinarily be used. As seen in FIG. 4, the connection member 45 may comprise a U-shaped channel member to which the ends 43 b of the struts 43 are pivotably connected and against the bottom 47 of which the ends of the struts abut so that the struts cannot pivot beyond a predetermined position, such as is disclosed in U.S. application Ser. No. 10/779,632, which is hereby incorporated by reference.

Tension members 49 can be provided to extend between the first ends 27 a, 27 a′ of the corner or second hub elements 27 and 27 a of the four folding frame elements 21, 21′, 21, 21′ and the second ends 43 b of the two strut members 43. The tension members 49 may function, either by themselves or together with a connection member 45, to prevent the ends 43 b of the two strut members from pivoting beyond the first plane. It will be appreciated that the second ends of the struts of the brace may lie in the second plane and that tension members may extend from second ends of the second hub elements, instead of the embodiment illustrated. The tension members 49 can be connected to the hub elements by means of tension member connection brackets 51 (FIGS. 5A-5D), which may be associated with the hub elements and can include mounting points for the tensions members. Tension member connection brackets 51 may also be attached to the connection member 45 to connect tension members 49 to the connection member.

The first hub element 25 and the second hub element 27 can be constructed to facilitate folding the frame elements and the frame system into a closed position in which the struts and hubs are substantially parallel to one another. The first hub element 25 and the second hub element 27 are ordinarily of similar or identical construction. Each typically comprises an elongated member with a first hub and a second hub at ends of the elongated member. Using the nomenclature of the first hub element 25 for purposes of illustration, as seen in FIG. 5A, the elongated member 53 comprises a first hub 55 at the first end 25 a of the hub element, and a second hub 57 at the second end 25 b of the hub element. As seen in phantom, the first end 29 a of the first strut 29 is pivotably connected to the first hub 55 at a first pivot point 59 and the first end 31 a of the second strut 31 is pivotably connected to the second hub 57 at a second pivot point 61. The first pivot point 59 is disposed at a greater distance D1 from an axis A of the elongated member 53 of the first hub element 25 than the distance D2 of the second pivot point 61 from the axis of the elongated member. More particularly, the first pivot point 59 is disposed at the greater distance than the second pivot point 61 from the axis of the elongated member 53 equal to at least a half a width W1 of the first strut 29 plus half a width W2 of the second strut 31. In this way, when, as seen in, e.g., FIG. 1B, the first and second struts 29 and 31 pivot so that they are parallel with the first hub element 25, the second strut will not interfere with the first strut. All of the first pivot points 59 will ordinarily be disposed at an equal radius from an axis of the elongated member 53, and all of the second pivot points 61 will ordinarily be disposed at an equal but smaller radius from the axis of the elongated member, however, the pivot points may be disposed at different radii.

Typically, the first and the second hubs 55 and 57 each comprise a plurality of first and second pivot points 59 and 61, respectively, with the number of second pivot points being equal to the number of first pivot points. The cable connection bracket 51 can be associated with the first hub.

The hub elements can be made from a few, relatively easily formed pieces, as seen with reference to FIGS. 5A-5D. In this embodiment, the elongated member 53 is a square or rectangular tubular element. Identical cable connection brackets 51 can be provided at the top and bottom of the hub elements. The cable connection brackets 51 are in the form of a plate having multiple holes 63 to which cables can be connected, such as by riveting. The brackets 51 may be provided with cutouts 65 to facilitate folding of the struts relative to the hub elements. A square or rectangular hole 67 is provided in the bracket to permit a portion of the first or second hubs 55 or 57 to extend therethrough.

The first hub 55 in the embodiment of FIGS. 5A-5D is formed from three parts. An inner portion 69 is formed from a square or rectangular plate that is bent to form a substantially downward facing U-shape having first and second legs 69 a and 69 b. Pivot holes 71 are formed in the plate so that, when the plate is bent to form the U-shape, the pivot holes will define an axis along which a pivot pin (not shown) for pivotably connecting the struts 29 and 31 and/or the diagonal member 33 will extend. Rivet holes 73 are provided in the plate for riveting the first end 53 a of the elongated member 53 to the first hub 55.

The first hub 55 also includes an outer portion 75 that is formed from a polygonal plate that is bent to form a substantially downward facing U-shape with, at ends of legs 75 a and 75 b of the U-shape, outwardly extending flanges 77 in which pivot holes 79 are provided so that, when the plate is bent to form the outer portion, the pivot holes will define an axis along which the pivot pin for pivotably connecting struts and/or a diagonal member can extend. Rivet holes 81 are provided in the plate for riveting the first end 53 a of the elongated member to the outer portion 75 and, through the rivet holes 73, to the inner portion 69. The cable connection bracket 51 is attached to the inner portion 69 and the outer portion 75 by fitting the U-shape of the outer portion through the square or rectangular hole 67 in the cable connection bracket and seating the cable connection bracket on top of the bottom of the U-shape of the inner portion. The cable connection bracket 51 may be secured to the inner and outer portions 69 and 75 by any suitable means, such as by a friction fit but, more likely by welding, brazing, adhesive, or riveting.

The second hub 57 in the embodiment of FIGS. 5A-5D is formed from three parts. An inner portion 89 is formed from a square or rectangular plate that is bent to form a substantially downward facing U-shape having first and second legs 89 a and 89 b. Pivot holes 91 are formed in the plate so that, when the plate is bent to form the U-shape, the pivot holes will define an axis along which a pivot pin (not shown) for pivotably connecting the struts 29 and 31 will extend. Rivet holes 93 are provided in the plate for riveting the second end 53 b of the elongated member 53 to the second hub 57.

The second hub 57 also includes an outer portion 95 that is formed from a polygonal plate that is bent to form a substantially upward facing U-shape with, at ends of legs 95 a and 95 b of the U-shape, outwardly extending flanges 97 in which pivot holes 99 are provided so that, when the plate is bent to form the outer portion, the pivot holes will define an axis along which the pivot pin for pivotably connecting struts and/or a diagonal member can extend. Rivet holes 101 are provided in the plate for riveting the second end 53 b of the elongated member to the outer portion 95 and, through the rivet holes 93, to the inner portion 79. The cable connection bracket 51 is attached to the inner portion 79 and the outer portion 95 by fitting the U-shape of the outer portion through the square or rectangular hole 67 in the cable connection bracket and seating the cable connection bracket on the ends of the legs of the U-shape of the inner portion. The cable connection bracket 51 may be secured to the inner and outer portions 79 and 95 by any suitable means, such as by a friction fit but, more likely by welding, brazing, adhesive, or riveting.

As seen in FIGS. 5A-5D, the pivot points 59 and 61, i.e., the axes defined by the pivot holes 71 and 79, and 91 and 99, respectively, are disposed such that, the first pivot point 59 is disposed at a greater distance D1 from an axis A of the elongated member 53 of the first hub element 25 than the distance D2 of the second pivot point 61 from the axis of the elongated member. More particularly, the first pivot point 59 is disposed at the greater distance than the second pivot point 61 from the axis of the elongated member 53 equal to at least a half a width W1 of the first strut 29 plus half a width W2 of the second strut 31. In this way, when, as seen in, e.g., FIG. 1B, the first and second struts 29 and 31 pivot so that they are parallel with the first hub element 25, the second strut will not interfere with the first strut.

A variety of structures can be function as the lock 35 for locking the first and second strut members 33 c and 33 d of the diagonal member 33 relative to each other when the struts 29 and 31 are pivoted to the open position relative to the first hub element 25. A spring loaded pin or lever arrangement is presently believed to be a useful structure for functioning as the lock and an embodiment is shown in FIGS. 6A-6D. The lock 35 comprises a lever member 103 pivotably pinned by a pin 105 inside one of the first and second strut members 33 c and 33 d. In the embodiment shown in FIGS. 6A-6B, the lever member 103 is pinned inside the first strut member 33 c. A spring 107 is mounted on the pivot pin 105. One end of the spring 107 abuts a flange 109 on the lever member 103 and the other end abuts the inside of the first strut member 33 c so the lever member is spring loaded to cause a lock end 111 thereof to extend outside of a first radial opening 113 in the first strut member. A lever end 115 of the lever member 103 extends outside of a second radial opening 117 in the first strut member 33 c to facilitate turning the lever member against the force of the spring 107.

At least an end portion of the first strut member 33 c from which the lock end 111 is adapted to protrude is sufficiently small to be received inside an end of the second strut member 33 d. The end of the second strut member 33 d has a radial opening 119 that aligns with the first radial opening 113 in the first strut member 33 c so that the lock end 111 can protrude through both the radial openings 113 and 119 to lock the first and second strut members relative to each other. The lever member 103 can be formed by bending a plate 121 having the general shape as shown in FIG. 6C into a U-shape so that pivot pin holes 123 align. As seen in FIG. 6D, a pair of diagonal members 33 on a frame element 21 can have locks 35 that are capable of being pivoted to unlock the strut members 33 c and 33 d by pulling on a common pull string 125 (shown in phantom) connected to the lever ends 115 of the lever member 103.

FIGS. 7A-7D show several embodiments of frame elements that can be made according to the present invention. In FIG. 7A, a frame element 21 having substantially parallel first and second hub elements 25 and 27 and substantially parallel first and second struts 29 and 31 is shown, wherein the diagonal member 33 is adapted to be locked by lock 35, when the struts are pivoted to the open position, in a position such that the frame element is substantially rectangular. In FIG. 7B, a frame element 221 having substantially parallel first and second hub elements 225 and 227 and substantially parallel first and second struts 229 and 231 is shown, wherein the diagonal member 233 is adapted to be locked by a lock 35, when the struts are pivoted to the open position, in a position such that the frame element is substantially rhomboidal. In both the embodiments of FIGS. 7A and 7B, the first and second struts are the same length. Ordinarily, neither of the first and second struts will be telescopic.

In FIG. 7C, a frame element 21′ having non-parallel first and second hub elements 25′ and 27′ and substantially parallel first and second struts 29′ and 31′ is shown, wherein the first strut is longer than the second strut when the diagonal member 33′ is locked by the lock 35′ and the struts are pivoted to the open position. The frame element 21′ has the shape of two mirror image trapezoids on opposite sides of the first hub element 25′, with the struts 29′ and 31′ being substantially parallel and the hub elements 25′ and 27′ being non-parallel. The second strut 31′ is telescopic to permit the struts and hub elements to fold to the closed position in which they are all substantially parallel.

In FIG. 7D, a frame element 221′ having non-parallel first and second hub elements 225′ and 227′ and non-parallel first and second struts 229′ and 231′ is shown, wherein the first strut is longer than the second strut when the diagonal member 233′ is locked by the lock 235′ and the struts are pivoted to the open position. The frame element 221′ has the shape of two mirror image trapezoids on opposite sides of the first hub element 225′, with the struts 229′ and 231′ being non-parallel and the hub elements 225′ and 227′ being non-parallel. The frame element 221′ differs from the frame element 21′ primarily in that the second strut 231′ is shorter than the second strut 31′ when in the open position (alternatively, the first strut 229′ could be longer than the first strut 29′). The diagonal member 233′ will also ordinarily be shorter than the diagonal member 33′.

Frame elements as shown in FIGS. 7A-7D, as well as other frame elements, can be combined to form a variety of frame systems. Ordinarily, the frame elements will be designed so that the second struts define particular angles with respect to each other, e.g., 30°, 45°, or 60°, so a system comprising a series of frame elements positioned end-to-end will define, e.g., an arch or some other useful structure. For example, FIGS. 8A-8D show frame systems 23, 223, 23′, and 223′ formed from the frame elements 21, 221, 21′, and 221′ shown in FIGS. 7A-7D, respectively. In the embodiments shown in FIGS. 8A and 8B, frame elements are combined with legs 127 that may be attached to or be integral with hub elements. The legs 127 can be extendable legs, such as by providing telescoping or foldable leg portions.

Frame elements such as 21, 221, 21′, and 221′ can be combined in a variety of ways to make various different structures. FIG. 9, for example, shows a system 323 in which a frame element 21 is combined with a frame element 221′. FIGS. 10A and 10B show end and side views of a system 423 in which a frame element 21 is combined with a frame element 221. FIG. 10C shows the system of FIGS. 10A and 10B in perspective and illustrates how ends of different types of frame elements can be connected together. FIG. 10D shows how the struts of the system of FIG. 10C can be folded to a closed position so the system has a size substantially smaller than the system of 10C in which all struts are pivoted to the open position. FIGS. 11A-11E, FIGS. 12A-12B, and FIGS. 13A-13B, respectively, show systems 623, and 723 that combine frame elements 21 and 21′ in different ways to create systems having different characteristics. The systems 623 and 723 show a further feature that can be provided, namely, a peak 131 portion that can comprise a strut 133 extending perpendicularly to a plane of a system, usually attached to the connection member 45 or the strut member 43, and over which a cover can be attached. The peak 131 can also comprise tension members 135 extending between the strut 133 and the second hub elements of the neighboring frame elements 21. Providing a peak on a structure such as the system 623 can be useful to prevent water, snow, ice, etc. from accumulating on the top of the structure.

FIGS. 14A-14D show steps in the erection of a system 423 of the type shown in FIGS. 10A-10E from a closed condition as seen in FIG. 14A to a fully open position as seen in FIG. 14D. In FIG. 14B it is seen that the frame elements 21 and 21′ are unfolded from the closed position of FIG. 14A toward the open position. This might be accomplished by the person(s) erecting the system 423 moving the leg members 127 outward, perpendicular to the ground. In FIG. 14C, struts of the frame elements 21 and 21′ are all moved to their open positions and their respective diagonal members 33 and 33′ are locked to lock the frame elements in their open positions. In FIG. 14D, the legs 127 are extended from the unextended condition (FIGS. 14A-14C) to the extended position. By extending the legs 127 subsequent to opening and locking the frame elements, the frame elements can be opened and locked by users standing at ground level, without ladders or the like being necessary. The legs 127 will ordinarily be lockable in the extended position by a suitable locking arrangement, which may be the same as the lock that is used to lock the diagonal members.

FIGS. 15A-15D show steps in the erection of a system 523 of the type shown in FIGS. 11A-11E from a closed condition as seen in FIG. 15A to a fully open position as seen in FIG. 15D. In FIG. 15B it is seen that the frame elements 21 and 21′ are unfolded from the closed position of FIG. 15A toward the open position. FIG. 15C shows that frame elements at the center or peak of the system 523 can be fully opened and locked in their open position first and, as seen in FIG. 15D, frame elements at the periphery of the system can be fully opened and locked in the open position subsequent to opening and locking the frame elements at the center of the system. In this way, the frame elements at the center of the system 523 can be opened and locked by users at ground level.

Inner and/or outer covers (not shown) will typically be provided on systems of the type shown in, e.g., FIGS. 8A-15D. The covers will typically be secured to the frame systems by connectors attached to inner and outer portions of the hub elements. Particularly, as seen in FIGS. 5C and 5D, the outer portions 75 and 95 of the first and second hubs 55 and 57 can be provided with mounting holes 129 through which mounting elements, e.g., bolts, hooks, etc., can extend and also extend through holes, such as in grommets, in the covers.

While the present invention has been described largely in connection with frame elements 21 wherein first and second struts 29 and 31 are rigid, in some circumstances it is possible and desirable to replace a rigid strut with a flexible tension member, such as a cable. This has been found to be a useful way of facilitating closing, i.e., collapsing, frame systems such as those shown in, e.g., FIGS. 12A-12B and 13A-13B. Thus, as used herein, the word “strut” is intended to encompass rigid members capable of withstanding loads in tension and compression as well as flexible members capable of withstanding only loads in tension. FIGS. 16A-16C show embodiments of frame systems 823, 923, and 1023 similar to the frame systems 323 and 423 wherein selected frame elements 21 and 21′ are replaced with struts in the form of tension members in the form of cables 1000 to facilitate folding of the frame systems.

In the present application, the use of terms such as “including” is open-ended and is intended to have the same meaning as terms such as “comprising” and not preclude the presence of other structure, material, or acts. Similarly, though the use of terms such as “can” or “may” is intended to be open-ended and to reflect that structure, material, or acts are not necessary, the failure to use such terms is not intended to reflect that structure, material, or acts are essential. To the extent that structure, material, or acts are presently considered to be essential, they are identified as such.

While this invention has been illustrated and described in accordance with a preferred embodiment, it is recognized that variations and changes may be made therein without departing from the invention as set forth in the claims. 

1. A folding frame element, comprising: a first hub element having a first end and a second end; a second hub element having a first end and a second end; a first strut pivotably attached at a first end and a second end to the first ends of the first hub element and the second hub element, respectively; a second strut pivotably attached at a first end and a second end to the second ends of the a diagonal member extending between the first end of the first hub element and the second end of the second hub element, wherein the first and second struts are pivotable relative to the first and second hub elements between a closed position in which the first and second struts and the first and second hub elements are substantially parallel and the diagonal member has a first length and an open position in which the first and second struts define non-zero angles with the first and second hub elements and the diagonal member has a second length shorter than the first length.
 2. The folding frame element as set forth in claim 1, wherein the diagonal member comprises a strut arrangement pivotably attached at a first end of the diagonal member to the first end of the first hub element and at a second end of the diagonal member to the second end of the second hub element.
 3. The folding frame element as set forth in claim 2, wherein the strut arrangement comprises telescoping strut members.
 4. The folding frame element as set forth in claim 3, wherein the strut arrangement comprises a lock for locking the telescoping strut members at the second length.
 5. The folding frame element as set forth in claim 1, wherein, when the first and second struts are pivoted to the closed position, a combined length of the first strut and the second hub element is substantially equal to a combined length of the second strut and the first hub element.
 6. The folding frame element as set forth in claim 5, wherein the second strut comprises telescoping strut members.
 7. The folding frame element as set forth in claim 6, wherein, when the first and second struts are pivoted to the open position, the telescoping strut members of the second strut are retracted to a shorter length than when the first and second struts are pivoted to the closed position.
 8. The folding frame element as set forth in claim 1, wherein the second strut comprises telescoping strut members.
 9. The folding frame element as set forth in claim 8, wherein, when the first and second struts are pivoted to the open position, the telescoping strut members of the second strut are retracted to a shorter length than when the first and second struts are pivoted to the closed position.
 10. The folding frame element as set forth in claim 9, wherein the diagonal member comprises a strut arrangement pivotably attached at a first end of the diagonal member to the first end of the first hub element and at a second end of the diagonal member to the second end of the second hub element, and wherein the strut arrangement comprises telescoping strut members.
 11. The folding frame element as set forth in claim 10, wherein the strut arrangement comprises a lock for locking the telescoping strut members at the second length.
 12. The folding frame element as set forth in claim 1, comprising a tension member extending between the first end of the second hub element and the second end of the first hub element.
 13. The folding frame element as set forth in claim 12, wherein the tension member is a cable.
 14. The folding frame element as set forth in claim 13, comprising a cable keeper connected to the cable.
 15. The folding frame element as set forth in claim 1, comprising a third hub element having a first end and a second end; a third strut pivotably attached at a first end and a second end to the first ends of the first hub element and the third hub element, respectively; a fourth strut pivotably attached at a first end and a second end to the second ends of the first hub element and the third hub element, respectively; and a second diagonal member extending between the first end of the first hub element and the second end of the third hub element, wherein the third and fourth struts are pivotable relative to the first and third hub elements between a closed position in which the third and fourth struts and the first and third hub elements are substantially parallel and the second diagonal member has a first length and an open position in which the third and fourth struts define non-zero angles with the first and third hub elements and the second diagonal member has a second length shorter than the first length.
 16. The folding frame element as set forth in claim 15, wherein the third hub element, the third strut, the fourth strut, and the second diagonal member are substantially mirror images of the second hub element, the third strut, the fourth strut, and the first diagonal member.
 17. The folding frame element as set forth in claim 1, wherein the first hub element comprises a first hub and a second hub at the first end and the second end, respectively, of the first hub element, the first end of the first strut being pivotably connected to the first hub at a first pivot point and the first end of the second strut being pivotably connected to the second hub at a second pivot point, the first pivot point being disposed at a greater distance from an axis of the first hub element than the second pivot point.
 18. The folding frame element as set forth in claim 17, wherein the first pivot point is disposed at the greater distance than the second pivot point from the axis of the first hub element equal to at least half a width of the first strut plus half a width of the second strut.
 19. The folding frame element as set forth in claim 1, wherein, when the first and second struts are pivoted to the open position, the first strut is longer than the second strut and the first hub element and the second hub element are non-parallel.
 20. The folding frame element as set forth in claim 19, wherein the second strut comprises telescoping strut members and, when the first and second struts are pivoted to the open position, the telescoping strut members of the second strut are retracted to a shorter length than when the first and second struts are pivoted to the closed position.
 21. The folding frame element as set forth in claim 19, wherein the first and second hub elements are substantially the same length.
 22. A folding frame element, comprising: a first hub element having a first and a second end; at least a pair of strut assemblies pivotably attached to the first hub element, each strut assembly comprising a second hub element having a first end and a second end, a first strut pivotably attached at a first end and a second end to the first ends of the first hub element and the second hub element, respectively, a second strut pivotably attached at a first end and a second end to the second ends of the first hub element and the second hub element, respectively, and a diagonal member extending between the first end of the first hub element and the second end of the second hub element, wherein the first and second struts are pivotable relative to the first and second hub elements between a closed position in which the first and second struts and the first and second hub elements are substantially parallel and the diagonal member has a first length and an open position in which the first and second struts define non-zero angles with the first and second hub elements and the diagonal member has a second length shorter than the first length.
 23. A folding frame system, comprising at least two folding frame elements as set forth in claim 22 connected end to end and sharing a common second hub element.
 24. The folding frame system as set forth in claim 23, wherein, for at least one of the at least two folding frame elements, at least one of the second struts comprises telescoping strut members and, when the first and second struts are pivoted to the open position, the telescoping strut members of the at least one of the second struts are retracted to a shorter length than when the first and second struts are pivoted to the closed position.
 25. The folding frame system as set forth in claim 24, wherein, when the first and second struts of the at least two folding frame elements are pivoted to the open position, the first and second struts of a first one of the at least two folding frame elements are non-parallel to the first and second struts of a second one of the at least two folding frame elements.
 26. The folding frame system as set forth in claim 23, wherein, for each strut assembly of each folding frame element, the diagonal member comprises a strut arrangement pivotably attached at a first end of the diagonal member to the first end of the first hub element and at a second end of the diagonal member to the second end of the second hub element, and wherein the strut arrangement comprises telescoping strut members.
 27. The folding frame system as set forth in claim 26, wherein the strut arrangement comprises a lock for locking the telescoping strut members at the second length.
 28. The folding frame system as set forth in claim 23, comprising a plurality of folding frame elements as set forth in claim 22 connected end to end in succession to define a polygonal shape, successive ones of the plurality of folding frame elements sharing common second hub elements.
 29. The folding frame system as set forth in claim 28, comprising four folding frame elements connected end to end in succession to define a substantially square shape.
 30. The folding frame system as set forth in claim 29, comprising a brace assembly extending between two first struts of two non-successive folding frame elements.
 31. The folding frame system as set forth in claim 30, wherein the brace assembly comprises two strut members pivotably connected at first ends thereof to second ends of respective ones of the two first struts of the two non-successive folding frame elements and at second ends thereof to each other.
 32. The folding frame system as set forth in claim 31, wherein, when the first and second struts of the four folding frame elements are pivoted to the closed position, the two strut members each have a first length and, when the first and second struts of the four folding frame elements are pivoted to the open position, the two strut members each have a second length that is shorter than the first length.
 33. The folding frame system as set forth in claim 31, wherein, when the first and second struts of the four folding frame elements are pivoted to the open position, the first ends of the first and second hub elements define a first plane and the second ends of the first and second hub elements define a second plane, the second ends of the two strut members being disposed substantially in the first plane.
 34. The folding frame system as set forth in claim 33, comprising tension members extending between the first ends the second hub elements of the four folding frame elements and the second ends of the two strut members.
 35. A hub element for a folding frame element, the hub element comprising an elongated member and a first hub and a second hub at a first end and a second end, respectively, of the elongated member, the first hub comprising a first pivot point for pivotably connecting a first strut and the second hub comprising a second pivot point for pivotably connecting a second strut, the first pivot point being disposed at a greater distance from an axis of the elongated member than the second pivot point.
 36. The hub element as set forth in claim 35, wherein the first pivot point is disposed at the greater distance than the second pivot point from the axis of the elongated member equal to at least half a width of the first strut plus half a width of the second strut.
 37. The hub element as set forth in claim 35, wherein the first hub comprises a plurality of first pivot points.
 38. The hub element as set forth in claim 37, wherein the second hub comprises a plurality of second pivot points equal in number to the plurality of first pivot points.
 39. The hub element as set forth in claim 35, comprising a cable connection bracket associated with the first hub. 